From: Fu Wei fu.wei@linaro.org
The counter frequency detection call(arch_timer_detect_rate) combines two ways to get counter frequency: system coprocessor register and MMIO timer. But in a specific timer init code, we only need one way to try: getting frequency from MMIO timer register will be needed only when we init MMIO timer; getting frequency from system coprocessor register will be needed only when we init arch timer.
This patch separates paths to determine frequency: Separate out the MMIO frequency and the sysreg frequency detection call, and use the appropriate one for the counter.
Signed-off-by: Fu Wei fu.wei@linaro.org --- drivers/clocksource/arm_arch_timer.c | 40 ++++++++++++++++++++++-------------- 1 file changed, 25 insertions(+), 15 deletions(-)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 6484f84..9482481 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -488,23 +488,33 @@ static int arch_timer_starting_cpu(unsigned int cpu) return 0; }
-static void arch_timer_detect_rate(void __iomem *cntbase) +static void __arch_timer_determine_rate(u32 rate) { - /* Who has more than one independent system counter? */ - if (arch_timer_rate) - return; + /* Check the timer frequency. */ + if (!arch_timer_rate) { + if (rate) + arch_timer_rate = rate; + else + pr_warn("frequency not available\n"); + } else if (rate && arch_timer_rate != rate) { + pr_warn("got different frequency, keep original.\n"); + } +}
+static void arch_timer_detect_rate(void) +{ /* - * Try to determine the frequency from the MMIO timer or the sysreg. + * Try to get the timer frequency from the sysreg CNTFRQ. */ - if (cntbase) - arch_timer_rate = readl_relaxed(cntbase + CNTFRQ); - else - arch_timer_rate = arch_timer_get_cntfrq(); + __arch_timer_determine_rate(arch_timer_get_cntfrq()); +}
- /* Check the timer frequency. */ - if (arch_timer_rate == 0) - pr_warn("frequency not available\n"); +static void arch_timer_mem_detect_rate(void __iomem *cntbase) +{ + /* + * Try to get the timer frequency from the CNTFRQ reg of MMIO timer. + */ + __arch_timer_determine_rate(readl_relaxed(cntbase + CNTFRQ)); }
static void arch_timer_banner(unsigned type) @@ -887,7 +897,7 @@ static int __init arch_timer_of_init(struct device_node *np) */ if (!arch_timer_rate && of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) - arch_timer_detect_rate(NULL); + arch_timer_detect_rate();
arch_timer_c3stop = !of_property_read_bool(np, "always-on");
@@ -1001,7 +1011,7 @@ static int __init arch_timer_mem_init(struct device_node *np) */ if (!arch_timer_rate && of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) - arch_timer_detect_rate(base); + arch_timer_mem_detect_rate(base);
ret = arch_timer_mem_register(base, irq); if (ret) @@ -1064,7 +1074,7 @@ static int __init arch_timer_acpi_init(struct acpi_table_header *table) gtdt->non_secure_el2_flags);
/* Get the frequency from the sysreg CNTFRQ */ - arch_timer_detect_rate(NULL); + arch_timer_detect_rate();
arch_timer_uses_ppi = arch_timer_select_ppi(); if (!arch_timer_ppi[arch_timer_uses_ppi]) {